1. Field of the Invention
The present invention relates generally to marine jet drive apparatus and more particularly to an improved ride plate assembly for attachment to the lower aft portion of a personal watercraft and including an integral rudder subassembly and appropriate linkage for linking the rudder assembly to the jet discharge nozzle so that it follows the orientation of the nozzle.
2. Brief Description of the Prior Art
Personal watercraft employing jet drive propulsion typically use a steering nozzle to direct the jet thrust to one side or the other and thereby cause a steering rotation or yaw of the vessel which in combination with the lower hull characteristics results in a turning maneuver. However, such steering inputs cause the vessel to turn only when there is sufficient thrust to overcome the momentum and directional drag of the vessel. In other words, the combination of thrust and steering angle are required to rotate the vessel.
Water-jet propelled vessels of the type in question are disclosed in the U.S. patents to Tachibana et al. (U.S. Pat. No. 4,231,315) and Murase (U.S. Pat. No. 4,689,020). Note, however, that non-wetted rudder mechanisms are used.
In many circumstances the operator of a jet-propelled personal watercraft will instinctively reduce or cut the throttle in an emergency situation, such as an imminent collision. This has the adverse effect that, even though the steering mechanism is rotated to one side, the required turning thrust is reduced and the vehicle continues in the forward direction until slowed by hull drag. The desirability of providing a positive turning rudder to jet drive units used in power boats has been recognized and provided for as disclosed in the U.S. patents to Wildhaber, Sr. (U.S. Pat. No. 4,779,553), Kiekhaefer (U.S. Pat. No. 3,943,876), and Woodfill (U.S. Pat. No. 3,906,885). However, in none of these disclosures has there been a suggestion as to how one would appropriately modify such apparatus for application to a personal watercraft. One cannot merely apply the disclosed devices to personal watercraft because the relationship of drive to hull, the loading characteristics and the maneuvering requirements and stability of the devices are substantially different.